With the increment of the memory operation speed, for 512 Mb DDR2 SDRAM, the heat generated from the memory chip in operation will cause that more the heat dissipation sheets are necessary for heat dissipation.
Referring to FIGS. 1 and 2, in the prior art, the 512 Mb DDR2 SDRAM of HYS72T h has a circuit board 91 which can be inserted into a slot of a computer. A plurality of memory chips are installed on the circuit board. One of a maim memory ship 92 is covered by a heat dissipating sheet 93. The heat dissipating sheet is a metal sheet and is fixed by a bending portion 941 and a buckling strip 94. The buckling strip 94 has two ends which are formed with hooks 942 for hooking the penetrating holes 951, 952 of the circuit board 100 (referring to FIGS. 1A and 1B). Thereby the heat dissipating sheet 93 is fixed.
In this prior art, the buckling strips of the heat dissipating sheet increase the cost and the assembly of the strips are tedious and time consumed. Specifically, the distance between two penetrating holes is smaller than the length of the heat dissipating sheet. It is difficult to align the heat dissipating sheet to the circuit board, and thus the work in assembly is tedious and time consumed. This is the defect in the prior art.